Inhibitors of ubiquitin e1

ABSTRACT

The present invention features pyrazolidinyl compounds, pharmaceutical compositions of substituted pyrazolidinyl compounds and methods of treating a patient suffering from cancer or viral infection, the method comprising administering to a patient one or more pyrazolidinyl compounds of the invention.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a divisional of U.S. patent application Ser.No. 12,842,346 filed on Jul. 23, 2010, which is a divisional of U.S.patent application Ser. No. 12/154,156, filed on May 19, 2008, which isa continuation-in-part of International Application No. PCT/US06/45032having an International filing date of Nov. 20, 2006, and which claimsthe benefit of U.S. provisional application No. 60/738,242, filed Nov.19, 2005, all of which applications are incorporated herein by referencein its entirety.

GOVERNMENT SUPPORT

Research supporting this application was carried out by the UnitedStates of America as represented by the Secretary, Department of Healthand Human Services.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention involves pyrazolidinyl compounds and methods andpharmaceutical compositions that comprise such compounds. Compounds ofthe invention can be effective to modulate the function of theubitquitylation system, regulate p53 and Mdm2 stability and activity aswell as to act as therapeutic agents in a variety of indications,particularly to treat cancer as well to treat viral infections,particularly to treat retroviral-infected mammalian cells.

2. Background

The development of cancer can depend on the accumulation of specificgenetic alterations that allow aberrant cell proliferation, includinggrowth of tumor cells. Protection from such aberrant growth is providedby several mechanisms that work by inducing apoptotic cell death incells undergoing oncogenic changes. Therefore, for a tumor cell tosurvive, it must acquire genetic alterations that perturb the linkbetween abnormal growth and cell death. The p53 tumor suppressor proteincan induce apoptotic cell death and plays a pivotal role in tumorsuppression. Wild type p53 functions as a transcriptional regulator tocoordinately control multiple pathways in cell cycling, apoptosis, andangiogenesis.

Loss of the ability to induce p53 or other loss of p53 activity can leadto uncontrolled cell proliferation of the affected cells and tumorgrowth. In approximately 50% of human cancers, a wild type p53 gene isnevertheless retained. In such cancers, the defect that frequentlyoccurs is a failure to stabilize and activate p53 to thereby preventtumor development.

The Mdm2 protein plays an important role in targeting the degradation ofp53 in normal cells to allow normal growth and development. Inparticular, inhibition of Mdm2 is required to allow activation of a p53response. In tumors with wild type p53, defects can occur that lead toincreased Mdm2 activity, whereby p53 function cannot be induced.

Ubiquitin-mediated proteolysis is an important pathway of non-lysosomalprotein degradation that controls the timed destruction of a number ofcellular regulatory proteins including p53. See Pagano, 1997 FASEB J.11:1067. Ubiquitin is an evolutionary highly conserved 76-amino acidpolypeptide which is abundantly present in eukaryotic cells. Theubiquitin pathway leads to the covalent attachment of poly-ubiquitinchains to target substrates which are then degraded by a multi-catalyticproteasome complex.

A number of the steps of regulating protein ubiquitination are known. Inparticular, initially the ubiquitin activating enzyme (E1) forms a highenergy thioester linkage with ubiquitin. Ubiquitin is then transferredto a reactive cysteine residue of one of many ubiquitin conjugatingenzymes known as Ubc or ubiquitin E2 enzymes. The final transfer ofubiquitin to a target protein involves one of many ubiquitin proteinligases (E3s). Mdm2 is such a ubiquitin ligase that mediates thetransfer of ubiquitin to p53. See also WO05047476.

The human immunodeficiency virus (HIV) including HIV type 1 (HIV-1, alsoreferred to as HTLV-III LAV or HTLV-III/LAV) and, to a lesser extent,human immunodeficiency virus type 2 (HIV-2) is the etiological agent ofthe acquired immune deficiency syndrome (AIDS) and related disorders.Barre-Sinoussi, et al., Science, 220:868-871 (1983).

Efforts to identify certain agents that can inhibit retroviralreplication by modulating ubiquitination of a host cell protein has beenreported. U.S. Patent Publication 2005/0112562.

It thus would be desirable to have new compounds that have use intreatment of undesired cell proliferation, including in treatmentagainst cancer cells, as well as for treatment against viral infections,particularly to treat retroviral-infected mammalian cells. It would beespecially desirable to have new compounds that could modulate orstabilize p53 activity by inhibiting Mdm2-mediated ubiquitination.

SUMMARY OF THE INVENTION

We have now found new pyrazolidinyl compounds and therapeutic uses ofsuch compounds.

In one aspect, compounds of the invention are useful as anti-canceragents.

In a further aspect, compounds of the invention are useful to a disorderor disease where inflammation or an immune response is exhibited.

In another aspect, compounds of the invention are useful in anti-viraltherapies, including to treat against a retroviral infection inmammalian cells, particularly an HIV infection.

We have found that preferred pyrazolidinyl compounds can stabilize p53and induce apoptosis in mammalian cells through selective inhibition ofubiquitin E1. Preferred pyrazolidinyl compounds additionally can inhibitMdm2 autoubiquitination, in vitro cyclin E degradation, and/orTNF-induced TRAF6 ubiquitination, as well as TNF-induced phosphorylationand degradation of IκBα in cells. See for instance, the results setforth in the Examples, which follow.

In a particular aspect, the invention provides compounds of thefollowing Formula (I), or pharmaceutically acceptable salt, solvate orhydrate thereof:

wherein,

each X is independently O, S or NR¹;

each R¹ is independently H, alkyl, alkenyl, alkynyl, cycloalkyl,aralkyl, or heteroaralkyl, is C(O)R, C(O)OR, or C(O)NRR², eachoptionally substituted with a substituent;

each R² is independently H, alkyl, alkenyl, alkynyl, cycloalkyl,aralkyl, or heteroaralkyl, each optionally substituted with asubstituent;

each R is independently H, alkyl, alkenyl, alkynyl, cycloalkyl, aralkyl,or heteroaralkyl, each optionally substituted with a substituent;

Y is H, alkyl, alkenyl, alkynyl, cycloalkyl, aralkyl, heteroaralkyl,aryl, heteroaryl, nitro, or halogen;

wherein the alkyl, alkenyl, alkynyl, cycloalkyl, aralkyl, heteroaralkyl,aryl, or heteroaryl groups may be substituted with H, halogen, nitro,cyano, alkoxy, thioalkoxy, NR³R⁴, S(O)R⁵, S(O)₂R⁵;

wherein each of R³ and R⁴ are independently selected from H, alkyl,aralkyl, or aryl;

wherein R⁵ is OH, OR³, NH₂, or NHR³;

Z is H, alkyl, alkenyl, alkynyl, cycloalkyl, aralkyl, heteroaralkyl,aryl, heteroaryl, halogen, C(O)R³, C(O)OR³, C(O)SR³, C(O)NR³R⁴, C(S)OR³,C(NR¹)OR³, C(NR¹)NR³R⁴; and

n is an integer of zero to 5.

In another aspect, the invention provides compounds of the followingFormula (II), or pharmaceutically acceptable salt, solvate or hydratethereof:

wherein,

each X is independently O, S or NR¹;

each R¹ is independently H, alkyl, alkenyl, alkynyl, cycloalkyl,aralkyl, or heteroaralkyl, is C(O)R, C(O)OR, or C(O)NRR², eachoptionally substituted with a substituent;

each R² is independently H, alkyl, alkenyl, alkynyl, cycloalkyl,aralkyl, or heteroaralkyl, each optionally substituted with asubstituent;

each R is independently H, alkyl, alkenyl, alkynyl, cycloalkyl, aralkyl,or heteroaralkyl, each optionally substituted with a substituent.

The present invention further provides methods of treating or preventingan undesired cell proliferation disease or disorder such as cancercomprising the administration of a pyrazolidinyl compound to a patientsusceptible to or suffering from an undesired cell proliferation diseaseor disorder such as cancer. Preferred methods of the invention aresuitable for use in anti-cancer therapies and comprise theadministration of one or more compounds of Formula I and/or Formula II,alone or in combination with other anti-cancer or anti-tumortherapeutics. Malignancies for treatment include both solid anddisseminated cancers.

In a further aspect, the invention provides methods of treating orpreventing a retroviral infection comprising the administration of apyrazolidinyl compound to mammalian cells infected with or susceptibleto infection by a retrovirus such as HIV. Such methods can includeadministering to a subject cells or a patient an effective amount of oneor more pyrazolidinyl compounds particularly one or more compounds ofFormula I and/or Formula II above. Preferably, such administrationdecreases or eliminates the pool of infected cells and/or decreases theviral population.

As discussed above, the invention also provides methods of treating orpreventing a disease or disorder where inflammation or an immuneresponse is exhibited comprising one or more pyrazolidinyl compounds(such as one or more compounds of Formulae I and/or II) to a subject.For instance, methods of the invention include treatment or preventionof a disease or disorder where inhibiting inflammation would have abeneficial effect, such as sepsis or severe sepsis, arthritis,inflammatory myocarditis, glomerulonephritis, inflammatory conditions ofthe gastrointestinal tract, such as inflammatory bowel disease,ulcerative colitis, and Crohn's Disease, inflammatory conditions of thecentral nervous system, asthma, lung fibrosis, glomerulonephritis,atherosclerosis, autoimmune encephalomyelitis, cystic fibrosis,rheumatoid arthritis, systemic inflammatory response syndrome and otherNF-κB-mediated inflammatory disease states.

Indeed, it has been found that compounds of the invention (includingcompounds of Formulae I and II) are effective inhibitors of NFκB and canprevent activation of NFκB. See the examples which follow. See also Yanget al., Cancer Research, 67(19): 9472-9481 (2007).

It also believed that compounds of the invention (including compounds ofFormulae I and II) can inhibit autophagy in mammalian cells, includingprimate cells such as human cells.

Therapeutic methods of the invention can also include the step ofidentifying that the subject is in need of treatment of diseases ordisorders described herein, e.g., identifying that the subject is inneed of treatment for cancer, or treatment for a disease or disorderwhere inflammation or an immune response is exhibited, or treatment fora retroviral infection. The identification can be in the judgment of asubject or a health professional and can be subjective (e.g., opinion)or objective (e.g., measurable by a test or a diagnostic method). Testsfor cancer are known and may include e.g. analysis of patient sample(e.g. biopsed tissue, or patient fluid such as blood, saliva, etc.) andfor cancer cells or protein markers of a cancer. Tests for retroviralinfection such as HIV infection are known in the art and includepolymerase chain reaction-based (PCR-based) amplification and detectionof viral RNA; Western blot detection of anti-HIV antibodies;agglutination assays for anti-HIV antibodies; ELISA-based detection ofHIV-specific antigens (e.g., p24); and line immunoassay (LIA). In eachof these methods, a sample of biological material, such as blood,plasma, semen, or saliva, is obtained from the subject to be tested.Thus, the methods of the invention can include the step of obtaining asample of biological material (such as a bodily fluid) from a subject;testing the sample to determine the presence or absence of detectablecancer of retroviral infection such as HIV infection, HIV particles, orHIV nucleic acids; and determining whether the subject is in need oftreatment according to the invention.

The methods delineated herein can further include the step of assessingor identifying the effectiveness of the treatment or prevention regimenin the subject by assessing the presence, absence, increase, or decreaseof a marker, including a marker or diagnostic measure of cancer or of aretroviral infection such as HIV infection, HIV replication, viral load,or expression of an HIV infection marker; preferably this assessment ismade relative to a measurement made prior to beginning the therapy. Suchassessment methodologies are known in the art and can be performed bycommercial diagnostic or medical organizations, laboratories, clinics,hospitals and the like. As described above, the methods can furtherinclude the step of taking a sample from the subject and analyzing thatsample. The sample can be a sampling of cells, genetic material, tissue,or fluid (e.g., blood, plasma, sputum, etc.) sample. The methods canfurther include the step of reporting the results of such analyzing tothe subject or other health care professional. The method can furtherinclude additional steps wherein (such that) the subject is treated forthe indicated disease or disease symptom.

As used herein, the terms “subject” and “patient” are usedinterchangeably. As used herein, the terms “subject” and “subjects”refer to an animal, preferably a mammal including a non-primate (e.g., acow, pig, horse, cat, dog, rat, and mouse) and a primate (e.g., amonkey, ape, monkey, or human), and more particularly a human. In oneembodiment, the subject is an immunocompromised or immunosuppressedmammal, particularly a human (e.g., an HIV infected patient). In anotherembodiment, the subject is a mammal suffering from undesired cellgrowth, particularly a cancer, such as a human suffering from cancer.

The present invention further provides pharmaceutical compositionscomprising one or more compounds according to Formulae I and/or FormulaII, or salts thereof or solvate thereof, and preferably at least onepharmaceutically acceptable carrier.

The present invention also comprises methods of modulating Mdm2autoubiquitination in a subject, which suitably comprise administeringto the subject one or more compounds of Formulae I and/or II as setforth above in an amount and under conditions sufficient to modulateMdm2 autoubiquitination. Preferably, the modulation is down-regulation.Effective dosage amounts and administration protocols can be readilydetermined empirically, e.g. by standard efficacy evaluations. Efficacyand thus Mdm2 autoubiquitination modulation can be assessed e.g. bytherapeutic benefit as discussed herein, such as in vitro or in vivotreatment against cancer or viral infection.

The invention further comprises methods of modulating E1 to a greaterextent than E2 or SUMO E1 in a subject, which suitably compriseadministering to the subject one or more compounds of Formulae I and/orII as set forth above in an amount and under conditions sufficient tomodulate E1 to a greater extent than E2 or SUMO E1. Effective dosageamounts and administration protocols can be readily determinedempirically, e.g. by standard efficacy evaluations. Efficacy and thusmodulation of E1 to a greater extent than E2 or SUMO E1 can be assessede.g. by therapeutic benefit as discussed herein, such as in vitro or invivo treatment against cancer or viral infection.

The invention also comprises methods of modulating E1 selectively in asubject, which suitably comprise administering to the subject one ormore compounds of Formula I and/or II as set forth above in an amountand under conditions sufficient to modulate E1 selectively underconditions such that the E1 is altered selectively. Effective dosageamounts and administration protocols can be readily determinedempirically, e.g. by standard efficacy evaluations. Efficacy and thusselective E1 modulation can be assessed e.g. by therapeutic benefit asdiscussed herein, such as in vitro or in vivo treatment against canceror viral infection.

Compounds of the invention also will be useful to probe the function ofthe ubiquitin system and in inhibiting non-proteasomal functions ofubiquitination. In addition to its role in proteasomal degradation oftarget proteins, the ubiquitin system is also involved in a number ofcellular processes unrelated to proteasomal degradation includingendocytosis, trafficking in the endosomal system, viral budding, DNArepair, nucleocytoplasmic trafficking and kinase activation. Prior tothe preferred present compounds, there have been limited tools thatallow probing of the role of the ubiquitin system in these processes

Other aspects of the invention are discussed invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A depicts inhibition of autoubiquitination of GST-Mdm2 in vitro inthe presence of various compounds identified through high throughputscreening.

FIG. 1B depicts the inhibition of formation of E1-Ub complex in vitro bycertain compounds. Labeled ubiquitin was used to examine the high-energythiolester linkage between E1 and ubiquitin.

FIG. 2A depicts the inhibition of ubiquitin conjugation of E1 and E2 bysome compounds, while others selectively inhibited only E2.

FIG. 2B depicts the effective prevention of E2-Ub conjugate formation byE1-selective inhibitors without preloading E1 with ubiquitin.

FIG. 2C depicts the inhibition of in vitro autoubiquitination of theRING finger E3 Mdm2 and the HECT domain E3 Nedd4.

FIG. 3 depicts the restoration of4-[4-(5-nitro-furan-2-ylmethylene)-3,5-dioxo-pyrazolidin-1-yl]-benzoicacid methyl acid-induced inhibition of cyclin E degradation in S100 byE1.

FIG. 4A depicts the inhibition of TNF-induced IκBα degradation by4-[4-(5-nitro-furan-2-ylmethylene)-3,5-dioxo-pyrazolidin-1-yl]-benzoicacid methyl acid.

FIG. 4B depicts the inhibition of TNF-induced IκBα phosphorylation by4-[4-(5-nitro-furan-2-ylmethylene)-3,5-dioxo-pyrazolidin-1-yl]-benzoicacid methyl acid.

FIG. 4C depicts the inhibition of TNF-induced TRAF6 ubiquitination by4-[4-(5-nitro-furan-2-ylmethylene)-3,5-dioxo-pyrazolidin-1-yl]-benzoicacid methyl acid.

FIG. 5A depicts the increase in the levels of Mdm2 and p53 in RPE cellsafter treatment with the E1 inhibitor4-[4-(5-nitro-furan-2-ylmethylene)-3,5-dioxo-pyrazolidin-1-yl]-benzoicacid methyl acid.

FIG. 5B depicts the results of reporter assays showing that the p53induced by4-[4-(5-nitro-furan-2-ylmethylene)-3,5-dioxo-pyrazolidin-1-yl]-benzoicacid methyl acid is transcriptionally active.

FIG. 6A depicts the induction of growth arrest in untransformed RPEcells by4-[4-(5-nitro-furan-2-ylmethylene)-3,5-dioxo-pyrazolidin-1-yl]-benzoicacid methyl acid, as measured by MTT assay.

FIG. 6B depicts the dose-depending killing of J588 mouse myeloma cellsby proteasome and E1 inhibitor by4-[4-(5-nitro-furan-2-ylmethylene)-3,5-dioxo-pyrazolidin-1-yl]-benzoicacid methyl acid.

FIGS. 7A and 7B show that the E1 inhibitor4-[4-(5-nitro-furan-2-ylmethylene)-3,5-dioxo-pyrazolidin-1-yl]-benzoicacid methyl acid can prevent or inhibit loading of E1 with ubiquitin incells.

FIG. 8 shows that the E1 inhibitor4-[4-(5-nitro-furan-2-ylmethylene)-3,5-dioxo-pyrazolidin-1-yl]-benzoicacid methyl acid can inhibit proteasome inhibitor-induced accumulationof ubiquitylated proteins.

FIGS. 9A and 9B show that the E1 inhibitor4-[4-(5-nitro-furan-2-ylmethylene)-3,5-dioxo-pyrazolidin-1-yl]-benzoicacid methyl acid interacts with ubiquitin E1 covalently.

FIG. 10 shows that the E1 inhibitor4-[4-(5-nitro-furan-2-ylmethylene)-3,5-dioxo-pyrazolidin-1-yl]-benzoicacid methyl acid blocks IL-1-induced activation of NFκB.

DETAILED DESCRIPTION OF THE INVENTION

As discussed above, we now provide new pyrazolidinyl compounds andtherapeutic uses of such compounds, including for use as anti-cancer andanti-viral agents.

Preferred pyrazolidinyl compounds can stabilize p53 and induce apoptosisin mammalian cells through selective inhibition of ubiquitin E1.Preferred pyrazolidinyl compounds additionally inhibit Mdm2autoubiquitination, in vitro cyclin E degradation, and TNF-induced TRAF6ubiquitination, as well as TNF-induced phosphorylation and degradationof IκBα in cells.

Therapeutic methods of invention include treating or preventingundesired cell growth, particularly cancer, tumors and the like. Morepreferably, the disease or disorder suitable for treatment by themethods of the invention include cancers selected from solid (tumors)and disseminated cancers particularly melanoma, carcinoma, leukemia,lymphoma, pediatric sarcoma, sarcoma, breast cancer, ovarian cancer,testicular cancer, prostate cancer, brain cancer, head or neck cancer,and lung cancer.

Therapeutic methods of the invention also include treating or preventingviral infections, particularly retroviral infections in mammalian cells,such as human cells infected with HIV.

Therapeutic methods of the invention further include treating orpreventing a disease or disorder where inflammation or an immuneresponse is exhibited, including NF-κB-mediated inflammatory diseasestates.

As discussed above, compounds of the following Formula (I), orpharmaceutically acceptable salt, solvate or hydrate thereof areprovided as well as use of such compounds in the treatment of thediseases and disorders disclosed herein:

wherein,

each X is independently O, S or NR¹;

each R¹ is independently H, alkyl, alkenyl, alkynyl, cycloalkyl,aralkyl, or heteroaralkyl, is C(O)R, C(O)OR, or C(O)NRR², eachoptionally substituted with a substituent;

each R² is independently H, alkyl, alkenyl, alkynyl, cycloalkyl,aralkyl, or heteroaralkyl, each optionally substituted with asubstituent;

each R is independently H, alkyl, alkenyl, alkynyl, cycloalkyl, aralkyl,or heteroaralkyl, each optionally substituted with a substituent;

Y is H, alkyl, alkenyl, alkynyl, cycloalkyl, aralkyl, heteroaralkyl,aryl, heteroaryl, nitro, or halogen;

wherein the alkyl, alkenyl, alkynyl, cycloalkyl, aralkyl, heteroaralkyl,aryl, or heteroaryl groups may be substituted with H, halogen, nitro,cyano, alkoxy, thioalkoxy, NR³R⁴, S(O)R⁵, S(O)₂R⁵;

wherein each of R³ and R⁴ are independently selected from H, alkyl,aralkyl, or aryl;

wherein R⁵ is OH, OR³, NH₂, or NHR³;

Z is H, alkyl, alkenyl, alkynyl, cycloalkyl, aralkyl, heteroaralkyl,aryl, heteroaryl, halogen, C(O)R³, C(O)OR³, C(O)SR³, C(O)NR³R⁴, C(S)OR³,C(NR¹)OR³, C(NR¹)NR³R⁴; and

n is an integer of from 0 to 5.

In one embodiment, X is oxygen. In another embodiment, Y is H, nitro oraryl. In a further embodiment, the aryl group is phenyl. Preferably, thephenyl group is substituted with S(O)₂R⁵, wherein R⁵ is NH₂.

In another embodiment, Z is H, C(O)OR³, or halogen. In a furtherembodiment, R³ is alkyl. In another further embodiment, halogen is Br.

In one embodiment, n is 1. In another embodiment, Z is substituted atthe para or ortho position.

In another aspect, compounds of the following Formula (II), orpharmaceutically acceptable salt, solvate or hydrate thereof areprovided as well as use of such compounds in the treatment of thediseases and disorders disclosed herein:

wherein,

each X is independently O, S or NR¹;

each R¹ is independently H, alkyl, alkenyl, alkynyl, cycloalkyl,aralkyl, or heteroaralkyl, is C(O)R, C(O)OR, or C(O)NRR², eachoptionally substituted with a substituent;

each R² is independently H, alkyl, alkenyl, alkynyl, cycloalkyl,aralkyl, or heteroaralkyl, each optionally substituted with asubstituent;

each R is independently H, alkyl, alkenyl, alkynyl, cycloalkyl, aralkyl,or heteroaralkyl, each optionally substituted with a substituent.

Specifically preferred compounds of the invention particularly for usein the therapeutic methods disclosed herein are the following (and saltsand solvates thereof):

-   4-[4-(5-nitro-furan-2-ylmethylene)-3,5-dioxo-pyrazolidin-1-yl]-benzoic    acid methyl acid;

-   4-[4-(5-Nitro-furan-2-ylmethylene)-3,5-dioxo-pyrazolidin-1-yl]-benzoic    acid ethyl ester;

-   4-(5-Nitro-furan-2-ylmethylene)-1-phenyl-pyrazolidine-3,5-dione;

-   4-Furan-2-ylmethylene-1-phenyl-pyrazolidine-3,5-dione;

-   4-[5-(3,5-Dioxo-1-phenyl-pyrazolidin-4-ylidenemethyl)-furan-2-yl]-benzenesulfonamide;

-   1-(3-Bromo-phenyl)-4-(5-nitro-furan-2-ylmethylene)-pyrazolidine-3,5-dione;    and

-   1-(4-Bromo-phenyl)-4-furan-2-ylmethylene-pyrazolidine-3,5-dione.

As used herein, the term “alkyl” refers to a straight-chained orbranched hydrocarbon group containing 1 to 12 carbon atoms. The term“lower alkyl” refers to a C1-C6 alkyl chain. Examples of alkyl groupsinclude methyl, ethyl, n-propyl, isopropyl, tert-butyl, and n-pentyl.Alkyl groups may be optionally substituted with one or moresubstituents.

The term “alkenyl” refers to an unsaturated hydrocarbon chain that maybe a straight chain or branched chain, containing 2 to 12 carbon atomsand at least one carbon-carbon double bond. Alkenyl groups may beoptionally substituted with one or more substituents.

The term “alkynyl” refers to an unsaturated hydrocarbon chain that maybe a straight chain or branched chain, containing the 2 to 12 carbonatoms and at least one carbon-carbon triple bond. Alkynyl groups may beoptionally substituted with one or more substituents.

The sp² or sp carbons of an alkenyl group and an alkynyl group,respectively, may optionally be the point of attachment of the alkenylor alkynyl groups.

The term “alkoxy” refers to an —O-alkyl radical. The term “ester” refersto a —C(O)O—R., where R is defined herein An “amido” is an —C(O)NH₂, andan “N-alkyl-substituted amido” is of the formula C(O)NHR, where R isdefined herein. The term “mercapto” refers to a —SH group.

As used herein, the term “halogen” or “halo” means —F, —Cl, —Br or —I.

As used herein, the term “haloalkyl” means and alkyl group in which oneor more (including all) the hydrogen radicals are replaced by a halogroup, wherein each halo group is independently selected from —F, —Cl,—Br, and —I. The term “halomethyl” means a methyl in which one to threehydrogen radical(s) have been replaced by a halo group. Representativehaloalkyl groups include trifluoromethyl, bromomethyl,1,2-dichloroethyl, 4-iodobutyl, 2-fluoropentyl, and the like.

The term “cycloalkyl” refers to a hydrocarbon 3-8 membered monocyclic or7-14 membered bicyclic ring system having at least one non-aromatic.Cycloalkyl groups may be optionally substituted with one or moresubstituents. In one embodiment, 0, 1, 2, 3, or 4 atoms of each ring ofa cycloalkyl group may be substituted by a substituent. Representativeexamples of cycloalkyl group include cyclopropyl, cyclopentyl,cyclohexyl, cyclobutyl, cycloheptyl, cyclooctyl, cyclononyl, andcyclodecyl.

The term “cyclic” or similar term refers to a hydrocarbon 3-8 memberedmonocyclic or 7-14 membered bicyclic ring system having at least onenon-aromatic ring, wherein the non-aromatic ring has some degree ofunsaturation. Cyclic groups may be optionally substituted with one ormore substituents. In one embodiment, 0, 1, 2, 3, or 4 atoms of eachring of a cyclic group may be substituted by a substituent. Examples ofcyclyl groups include cyclohexenyl, bicyclo[2.2.1]hept-2-enyl,dihydronaphthalenyl, benzocyclopentyl, cyclopentenyl, cyclopentadienyl,cyclohexenyl, cyclohexadienyl, cycloheptenyl, cycloheptadienyl,cycloheptatrienyl, cyclooctenyl, cyclooctadienyl, cyclooctatrienyl,cyclooctatetraenyl, cyclononenyl, cyclononadienyl, cyclodecenyl,cyclodecadienyl and the like.

The term “aryl” refers to a hydrocarbon monocyclic, bicyclic ortricyclic aromatic ring system. Aryl groups may be optionallysubstituted with one or more substituents. In one embodiment, 0, 1, 2,3, 4, 5 or 6 atoms of each ring of an aryl group may be substituted by asubstituent. Examples of aryl groups include phenyl, naphthyl,anthracenyl, fluorenyl, indenyl, azulenyl, and the like.

As used herein, the term “aralkyl” means an aryl group that is attachedto another group by a (C₁-C₆)alkylene group. Aralkyl groups may beoptionally substituted, either on the aryl portion of the aralkyl groupor on the alkylene portion of the aralkyl group, with one or moresubstituent. Representative aralkyl groups include benzyl,2-phenyl-ethyl, naphth-3-yl-methyl and the like.

As used herein, the term “alkylene” refers to an alkyl group that hastwo points of attachment. The term “(C₁-C₆)alkylene” refers to analkylene group that has from one to six carbon atoms. Non-limitingexamples of alkylene groups include methylene (—CH₂—), ethylene(—CH₂CH₂—), n-propylene (—CH₂CH₂CH₂—), isopropylene (—CH₂CH(CH₃)—), andthe like.

The term “arylalkoxy” refers to an alkoxy substituted with aryl.

The term “heteroaryl” refers to an aromatic 5-8 membered monocyclic,8-12 membered bicyclic, or 11-14 membered tricyclic ring system having1-4 ring heteroatoms if monocyclic, 1-6 heteroatoms if bicyclic, or 1-9heteroatoms if tricyclic, said heteroatoms selected from O, N, or S, andthe remainder ring atoms being carbon (with appropriate hydrogen atomsunless otherwise indicated). Heteroaryl groups may be optionallysubstituted with one or more substituents. In one embodiment, 0, 1, 2,3, or 4 atoms of each ring of a heteroaryl group may be substituted by asubstituent. Examples of heteroaryl groups include pyridyl,1-oxo-pyridyl, furanyl, benzo[1,3]dioxolyl, benzo[1,4]dioxinyl, thienyl,pyrrolyl, oxazolyl, oxadiazolyl, imidazolyl thiazolyl, isoxazolyl,quinolinyl, pyrazolyl, isothiazolyl, pyridazinyl, pyrimidinyl,pyrazinyl, triazinyl, triazolyl, thiadiazolyl, isoquinolinyl, indazolyl,benzoxazolyl, benzofuryl, indolizinyl, imidazopyridyl, tetrazolyl,benzimidazolyl, benzothiazolyl, benzothiadiazolyl, benzoxadiazolyl,indolyl, tetrahydroindolyl, azaindolyl, imidazopyridyl, quinazolinyl,purinyl, pyrrolo[2,3]pyrimidinyl, pyrazolo[3,4]pyrimidinyl, andbenzo(b)thienyl, 3H-thiazolo[2,3-c][1,2,4]thiadiazolyl,imidazo[1,2-d]-1,2,4-thiadiazolyl, imidazo[2,1-b]-1,3,4-thiadiazolyl,1H,2H-furo[3,4-d]-1,2,3-thiadiazolyl,1H-pyrazolo[5,1-c]-1,2,4-triazolyl, pyrrolo[3,4-d]-1,2,3-triazolyl,cyclopentatriazolyl, 3H-pyrrolo[3,4-c]isoxazolyl,1H,3H-pyrrolo[1,2-c]oxazolyl, pyrrolo[2,1b]oxazolyl, and the like.

As used herein, the term “heteroaralkyl” or “heteroarylalkyl” means aheteroaryl group that is attached to another group by a (C₁-C₆)alkylene.Heteroaralkyl groups may be optionally substituted, either on theheteroaryl portion of the heteroaralkyl group or on the alkylene portionof the heteroaralkyl group, with one or more substituent. Representativeheteroaralkyl groups include 2-(pyridin-4-yl)-propyl,2-(thien-3-yl)-ethyl, imidazol-4-yl-methyl and the like.

The term “heterocycloalkyl” refers to a nonaromatic 5-8 memberedmonocyclic, 8-12 membered bicyclic, or 11-14 membered tricyclic ringsystem comprising 1-3 heteroatoms if monocyclic, 1-6 heteroatoms ifbicyclic, or 1-9 heteroatoms if tricyclic, said heteroatoms selectedfrom O, N, S, B, P or Si. Heterocycloalkyl groups may be optionallysubstituted with one or more substituents.

In one embodiment, 0, 1, 2, 3, or 4 atoms of each ring of aheterocycloalkyl group may be substituted by a substituent.Representative heterocycloalkyl groups include piperidinyl, piperazinyl,2-oxopiperazinyl, 2-oxopiperidinyl, 2-oxopyrrolidinyl, 4-piperidonyl,tetrahydropyranyl, tetrahydrothiopyranyl, tetrahydrothiopyranyl sulfone,morpholinyl, thiomorpholinyl, thiomorpholinyl sulfoxide, thiomorpholinylsulfone, 1,3-dioxolane, tetrahydrofuranyl, tetrahydrothienyl, thiirene.

The term “heterocyclyl” refers to a nonaromatic 5-8 membered monocyclic,8-12 membered bicyclic, or 11-14 membered tricyclic ring systemcomprising 1-3 heteroatoms if monocyclic, 1-6 heteroatoms if bicyclic,or 1-9 heteroatoms if tricyclic, said heteroatoms selected from O, N, S,B, P or Si, wherein the nonaromatic ring system has some degree ofunsaturation. Heterocyclyl groups may be optionally substituted with oneor more substituents. In one embodiment, 0, 1, 2, 3, or 4 atoms of eachring of a heterocyclyl group may be substituted by a substituent.Examples of these groups include thiirenyl, thiadiazirinyl, dioxazolyl,1,3-oxathiolyl, 1,3-dioxolyl, 1,3-dithiolyl, oxathiazinyl, dioxazinyl,dithiazinyl, oxadiazinyl, thiadiazinyl, oxazinyl, thiazinyl,1,4-oxathiin,1,4-dioxin, 1,4-dithiin, 1H-pyranyl, oxathiepinyl,5H-1,4-dioxepinyl, 5H-1,4-dithiepinyl,6H-isoxazolo[2,3-d]1,2,4-oxadiazolyl,7aH-oxazolo[3,2-d]1,2,4-oxadiazolyl, and the like.

The term “alkylamino” refers to an amino substituent which is furthersubstituted with one or two alkyl groups. The term “aminoalkyl” refersto an alkyl substituent which is further substituted with one or moreamino groups. The term “mercaptoalkyl” refers to an alkyl substituentwhich is further substituted with one or more mercapto groups. The term“hydroxyalkyl” or “hydroxylalkyl” refers to an alkyl substituent whichis further substituted with one or more hydroxyl groups. The term“sulfonylalkyl” refers to an alkyl substituent which is furthersubstituted with one or more sulfonyl groups. The term “sulfonylaryl”refers to an aryl substituent which is further substituted with one ormore sulfonyl groups. The term alkylcarbonyl refers to an —C(O)-alkyl.The term “mercaptoalkoxy” refers to an alkoxy substituent which isfurther substituted with one or more mercapto groups.

The term “alkylcarbonylalkyl” refers to an alkyl substituent which isfurther substituted with —C(O)-alkyl. The alkyl or aryl portion ofalkylamino, aminoalkyl, mercaptoalkyl, hydroxyalkyl, mercaptoalkoxy,sulfonylalkyl, sulfonylaryl, alkylcarbonyl, and alkylcarbonylalkyl maybe optionally substituted with one or more substituents.

As used herein the term “substituent” or “substituted” means that ahydrogen radical on a compound or group (such as, for example, alkyl,alkenyl, alkynyl, alkylene, aryl, aralkyl, heteroaryl, heteroaralkyl,cycloalkyl, cyclyl, heterocycloalkyl, or heterocyclyl group) is replacedwith any desired group that do not substantially adversely affect thestability of the compound. In one embodiment, desired substituents arethose which do not adversely affect the activity of a compound. The term“substituted” refers to one or more substituents (which may be the sameor different), each replacing a hydrogen atom. Examples of substituentsinclude, but are not limited to, halogen (F, Cl, Br, or I), hydroxyl,amino, alkylamino, arylamino, dialkylamino, diarylamino, cyano, nitro,mercapto, oxo (i.e., carbonyl), thio, imino, formyl, carbamido,carbamyl, carboxyl, thioureido, thiocyanato, sulfoamido, sulfonylalkyl,sulfonylaryl, alkyl, alkenyl, alkoxy, mercaptoalkoxy, aryl, heteroaryl,cyclyl, heterocyclyl, wherein alkyl, alkenyl, alkyloxy, aryl,heteroaryl, cyclyl, and heterocyclyl are optionally substituted withalkyl, aryl, heteroaryl, halogen, hydroxyl, amino, mercapto, cyano,nitro, oxo (═O), thioxo (═S), or imino (═NR^(c)).

In other embodiments, substituents on any group (such as, for example,alkyl, alkenyl, alkynyl, aryl, aralkyl, heteroaryl, heteroaralkyl,cycloalkyl, cyclyl, heterocycloalkyl, and heterocyclyl) can be at anyatom of that group, wherein any group that can be substituted (such as,for example, alkyl, alkenyl, alkynyl, aryl, aralkyl, heteroaryl,heteroaralkyl, cycloalkyl, cyclyl, heterocycloalkyl, and heterocyclyl)can be optionally substituted with one or more substituents (which maybe the same or different), each replacing a hydrogen atom. Examples ofsuitable substituents include, but not limited to alkyl, alkenyl,alkynyl, cyclyl, cycloalkyl, heterocyclyl, heterocycloalkyl, aralkyl,heteroaralkyl, aryl, heteroaryl, halogen, haloalkyl, cyano, nitro,alkoxy, aryloxy, hydroxyl, hydroxylalkyl, oxo (i.e., carbonyl),carboxyl, formyl, alkylcarbonyl, alkylcarbonylalkyl, alkoxycarbonyl,alkylcarbonyloxy, aryloxycarbonyl, heteroaryloxy, heteroaryloxycarbonyl,thio, mercapto, mercaptoalkyl, arylsulfonyl, amino, aminoalkyl,dialkylamino, alkylcarbonylamino, alkylaminocarbonyl, oralkoxycarbonylamino; alkylamino, arylamino, diarylamino, alkylcarbonyl,or arylamino-substituted aryl; arylalkylamino, aralkylaminocarbonyl,amido, alkylaminosulfonyl, arylaminosulfonyl, dialkylaminosulfonyl,alkylsulfonylamino, arylsulfonylamino, imino, carbamido, carbamyl,thioureido, thiocyanato, sulfoamido, sulfonylalkyl, sulfonylaryl, ormercaptoalkoxy.

Additional suitable substituents an alkyl, alkenyl, alkynyl, aryl,aralkyl, heteroaryl, heteroaralkyl, cycloalkyl, cyclyl,heterocycloalkyl, and heterocyclyl include, without limitation halogen,CN, NO₂, OR¹⁵, SR¹⁵, S(O)₂OR¹⁵, NR¹⁵R¹⁶, C₁-C₂ perfluoroalkyl, C₁-C₂perfluoroalkoxy, 1,2-methylenedioxy, (═O), (═S), (═NR¹⁵), C(O)OR¹⁵,C(O)NR¹⁵R¹⁶, OC(O)NR¹⁵R¹⁶, NR¹⁵C(O)NR¹⁵R¹⁶, C(NR¹⁶)NR¹⁵R¹⁶NR¹⁵C(NR¹⁶)NR¹⁵R¹⁶, S(O)₂ NR¹⁵R¹⁶, R¹⁷, C(O)H, C(O)R¹⁷, NR¹⁵C(O)R¹⁷,Si(R¹⁵)₃, OSi(R¹⁵)₃, Si(OH)₂R¹⁵, B(OH)₂, P(O)(OR¹⁵)₂, S(O)R¹⁷, orS(O)₂R¹⁷. Each R¹⁵ is independently hydrogen, C₁-C₆ alkyl optionallysubstituted with cycloalkyl, aryl, heterocyclyl, or heteroaryl. Each R¹⁶is independently hydrogen, C₃-C₆ cycloalkyl, aryl, heterocyclyl,heteroaryl, C₁-C₄ alkyl or C₁-C₄ alkyl substituted with C₃-C₆cycloalkyl, aryl, heterocyclyl or heteroaryl. Each R¹⁷ is independentlyC₃-C₆ cycloalkyl, aryl, heterocyclyl, heteroaryl, C₁-C₄ alkyl or C₁-C₄alkyl substituted with C₃-C₆ cycloalkyl, aryl, heterocyclyl orheteroaryl. Each C₃-C₆ cycloalkyl, aryl, heterocyclyl, heteroaryl andC₁-C₄ alkyl in each R¹⁵, R¹⁶ and R¹⁷ can optionally be substituted withhalogen, CN, C₁-C₄ alkyl, OH, C₁-C₄ alkoxy, COOH, C(O)OC₁-C₄ alkyl, NH₂,C₁-C₄ alkylamino, or C₁-C₄ dialkylamino.

As used herein, the term “lower” refers to a group having up to sixatoms. For example, a “lower alkyl” refers to an alkyl radical havingfrom 1 to 6 carbon atoms, and a “lower alkenyl” or “lower alkynyl”refers to an alkenyl or alkynyl radical having from 2 to 6 carbon atoms,respectively.

The recitation of a listing of chemical groups in any definition of avariable herein includes definitions of that variable as any singlegroup or combination of listed groups.

Combinations of substituents and variables envisioned by this inventionare preferably those that result in the formation of stable compounds.The term “stable”, as used herein, refers to compounds which possessstability sufficient to allow manufacture and which maintains theintegrity of the compound for a sufficient period of time to be usefulfor the purposes detailed herein (e.g., formulation into therapeuticproducts, intermediates for use in production of therapeutic compounds,isolatable or storable intermediate compounds, treating diseases,disorders or symptoms thereof). The compounds produced by the methodsherein can be incorporated into compositions, including solutions,capsules, crémes, or ointments for administration to a subject (e.g.,human, animal). Such compositions (e.g., pharmaceuticals) are useful forproviding to the subject desirable health or other physiologicalbenefits that are associated with such compounds.

The compounds of this invention include the compounds themselves, aswell as their salts, solvate, hydrate, polymorph, or prodrugs, ifapplicable.

The term “pharmaceutically acceptable salt” also refers to a saltprepared from a compound of any one of the formulae disclosed hereinhaving an acidic functional group, such as a carboxylic acid functionalgroup, and a pharmaceutically acceptable inorganic or organic base.Suitable bases include, but are not limited to, hydroxides of alkalimetals such as sodium, potassium, and lithium; hydroxides of alkalineearth metal such as calcium and magnesium; hydroxides of other metals,such as aluminum and zinc; ammonia, and organic amines, such asunsubstituted or hydroxy-substituted mono-, di-, or trialkylamines;dicyclohexylamine; tributyl amine; pyridine; N-methyl,N-ethylamine;diethylamine; triethylamine; mono-, bis-, or tris-(2-hydroxy-lower alkylamines), such as mono-, bis-, or tris-(2-hydroxyethyl)amine,2-hydroxy-tert-butylamine, or tris-(hydroxymethyl)methylamine,N,N,-di-lower alkyl-N-(hydroxy lower alkyl)-amines, such asN,N-dimethyl-N-(2-hydroxyethyl)amine, or tri-(2-hydroxyethyl)amine;N-methyl-D-glucamine; and amino acids such as arginine, lysine, and thelike. The term “pharmaceutically acceptable salt” also refers to a saltprepared from a compound of any one of the formulae disclosed hereinhaving a basic functional group, such as an amino functional group, anda pharmaceutically acceptable inorganic or organic acid. Suitable acidsinclude hydrogen sulfate, citric acid, acetic acid, oxalic acid,hydrochloric acid (HCl), hydrogen bromide (HBr), hydrogen iodide (HI),nitric acid, phosphoric acid, lactic acid, salicylic acid, tartaricacid, ascorbic acid, succinic acid, maleic acid, besylic acid, fumaricacid, gluconic acid, glucaronic acid, formic acid, benzoic acid,glutamic acid, methanesulfonic acid, ethanesulfonic acid,benzenesulfonic acid, and p-toluenesulfonic acid.

The compounds herein are commercially available or can be synthesized.As can be appreciated by the skilled artisan, methods of synthesizingthe compounds of the formulae herein will be evident to those ofordinary skill in the art. Additionally, the various synthetic steps maybe performed in an alternate sequence or order to give the desiredcompounds. Synthetic chemistry transformations and protecting groupmethodologies (protection and deprotection) useful in synthesizing thecompounds described herein are known in the art and include, forexample, those such as described in R. Larock, Comprehensive OrganicTransformations, 2nd. Ed., Wiley-VCH Publishers (1999); T. W. Greene andP. G. M. Wuts, Protective Groups in Organic Synthesis, 3rd. Ed., JohnWiley and Sons (1999); L. Fieser and M. Fieser, Fieser and Fieser'sReagents for Organic Synthesis, John Wiley and Sons (1999); and L.Paquette, ed., Encyclopedia of Reagents for Organic Synthesis, JohnWiley and Sons (1995), and subsequent editions thereof.

The compounds herein may contain one or more asymmetric centers and thusoccur as racemates and racemic mixtures, single enantiomers, individualdiastereomers and diastereomeric mixtures. All such isomeric forms ofthese compounds are expressly included in the present invention. Thecompounds herein may also contain linkages (e.g., carbon-carbon bonds)wherein bond rotation is restricted about that particular linkage, e.g.restriction resulting from the presence of a ring or double bond.Accordingly, all cis/trans and E/Z isomers are expressly included in thepresent invention. The compounds herein may also be represented inmultiple tautomeric forms, in such instances, the invention expresslyincludes all tautomeric forms of the compounds described herein, eventhough only a single tautomeric form may be represented (e.g.,alkylation of a ring system may result in alkylation at multiple sites,the invention expressly includes all such reaction products). All suchisomeric forms of such compounds herein are expressly included in thepresent invention. All crystal forms and polymorphs of the compoundsdescribed herein are expressly included in the present invention. Theterm “N-oxides” refers to one or more nitrogen atoms, when present in anaromatic ring nitrogen-containing compound, that are in N-oxideoxidation form, i.e., N→O.

As discussed above, preferred pyrazolidinyl compounds are useful incancer therapies. Preferred compounds of the formulae herein showsspecificity in cells for inhibiting the E1 for ubiquitin relative to theubiquitin-like modifier SUMO and does not inhibit E2 (UbCH5B). Thesepreferred compounds inhibit ubiquitin-mediated degradation of substratesboth in vitro and in cells, including the NFκB inhibitor (IcBat) andp53. They cause selective cell death of myeloma cells and of transformedp53-expressing fibroblasts that are predicted to be susceptible toapoptotic cell death in response to p53 reactivation. The compounds alsoactivate a p53 response in cells. These E1 inhibitors are not onlyunique and valuable tools to probe the ubiquitination system, but alsothe basis for development of therapeutic agents that, among otherthings, can target NFκB to suppress inflammation, activate p53, andotherwise interfere with normal ubiquitin-mediated processes to killtumor cells.

As discussed above, it has been found that pyrazolidinyl compounds ofthe present invention including those compounds represented by FormulaeI and II above are capable of stabilizing p53. Although not being boundby any theory, it is believed that preferred compounds of the inventioncan stabilize p53 activity in transformed cells by inhibition of Mdm2.More particularly, it is believed compounds of the invention, includingthose compounds of Formulae I and II above, are capable of inhibitingthe activity through inhibition of ubiquitin E1.

As discussed above, the invention includes methods for treating orpreventing (prophylactic treatment) against undesired cell growth orproliferation.

Preferred therapeutic methods of the invention include treatingmalignancies, including solid tumors and disseminated cancers. Exemplarytumors that may be treated in accordance with the invention include e.g.cancers of the lung, prostate, breast, liver, colon, breast, kidney,pancreas, brain, skin including malignant melanoma and Kaposi's sarcoma,testes or ovaries, or leukemias or lymphomia including Hodgkin'sdisease.

As also discussed above, the invention includes methods for treatingagainst a virus infection, including to treat mammalian cells that areinfected with a retrovirus, particularly human cells that are infectedwith a retrovirus such as HIV.

As discussed above, the invention also provides methods of treating orpreventing a disease or disorder where inflammation or an immuneresponse is exhibited comprising one or more pyrazolidinyl compounds toa subject, including one or more compounds of Formulae I or II.

The therapeutic methods of the invention generally compriseadministration of an effective amount of one or more compounds of theinvention to cells or a subject including a mammal, such as a primate,especially a human, in need of such treatment. The methods hereininclude administering to the subject (including a subject identified asin need of such treatment) an effective amount of a compound describedherein, or a composition described herein to produce such effect.Identifying a subject in need of such treatment can be in the judgmentof a subject or a health care professional and can be subjective (e.g.opinion) or objective (e.g. measurable by a test or diagnostic method).

The treatment methods of the invention also will be useful for treatmentof mammals other than humans, including for veterinary applications suchas to treat horses and livestock e.g. cattle, sheep, cows, goats, swineand the like, and pets (companion animals) such as dogs and cats.

For diagnostic or research applications, a wide variety of mammals willbe suitable subjects including rodents (e.g. mice, rats, hamsters),rabbits, primates and swine such as inbred pigs and the like.Additionally, for in vitro applications, such as in vitro diagnostic andresearch applications, body fluids (e.g., blood, plasma, serum, cellularinterstitial fluid, saliva, feces and urine) and cell and tissue samplesof the above subjects will be suitable for use.

Compounds of the invention may be administered singularly (i.e., soletherapeutic agent of a regime) to treat or prevent diseases andconditions such as undesired cell proliferation and/or viral infectionas disclosed herein.

Compounds of the invention also may be administered as a “cocktail”formulation, i.e., coordinated administration of one or more compoundsof the invention together with one or more other active therapeutics.

For instance, for a chemotherapy application, one or more pyrazolidinylcompounds of the invention including those of Formulae I and II may beadministered in coordination with a regime of one or more otherchemotherapeutic agents, particularly a compound that functions againstcancer cells other than by p53 stabilization such as an antineoplasticdrug, e.g., an alkylating agent (e.g., mechloroethamine, chlorambucil,cyclophosamide, melphalan, or ifosfamide), an antimetabolite such as afolate antagonist (e.g., methotrexate), a purine antagonist (e.g.6-mercaptopurine) or a pyrimidine antagonist (e.g., 5-fluorouracil).Other, non-limiting examples of chemotherapeutic agents that might beused in coordination with one or more compounds of the invention includetaxanes and topoisomerase inhibitors. In addition, other non-limitingexamples of active therapeutics include biological agents, such asmonoclonal antibodies or IgG chimeric molecules, that achieve theirtherapeutic effect by specifically binding to a receptor or ligand in asignal transduction pathway associated with cancer.

A particularly suitable combination protocol may include coordinatedadministration of one or more compounds of the invention with a compoundthat can activate but not necessarily stabilize p53, e.g. a therapeuticagent that can enhance interaction of p53 with histone acetylases.

For an antiviral therapy, one or more pyrazolidinyl compounds of theinvention including those of Formula I may be administered incoordination with a regime of one or more other antiviral agents such asreverse transcriptase inhibitors such as dideoxynucleosides, e.g.zidovudine (AZT), 2′,3′-dideoxyinosine (ddI) and 2′,3′-dideoxycytidine(ddC), lamivudine (3TC), stavudine (d4T), and TRIZIVIR(abacavir+zidovudine+lamivudine), nonnucleosides, e.g., efavirenz(DMP-266, DuPont Pharmaceuticals/Bristol Myers Squibb), nevirapine(Boehringer Ingleheim), and delaviridine (Pharmacia-Upjohn), TATantagonists such as Ro 3-3335 and Ro 24-7429, protease inhibitors, e.g.,indinavir (Merck), ritonavir (Abbott), saquinavir (Hoffmann LaRoche),nelfinavir (Agouron Pharmaceuticals), 141 W94 (Glaxo-Wellcome),atazanavir (Bristol Myers Squibb), amprenavir (GlaxoSmithKline),fosamprenavir (GlaxoSmithKline), tipranavir (Boehringer Ingleheim),KALETRA (lopinavir+ritonavir, Abbott), and other agents such as9-(2-hydroxyethoxymethyl)guanine (acyclovir), interferon, e.g.,alpha-interferon, interleukin II, and phosphonoformate (Foscarnet), orentry inhibitors, e.g., T20 (enfuvirtide, Roche/Trimeris) or UK-427,857(Pfizer), or in conjunction with other immune modulation agents ortreatments including bone marrow or lymphocyte transplants or othermedications such as levamisol or thymosin which would increaselymphocyte numbers and/or function as is appropriate. Because many ofthese drugs are directed to different targets, e.g., viral integration,a synergistic may result with this combination.

In one embodiment, one or more compounds of the invention includingthose of the formulae herein are used in conjunction with one or moretherapeutic agents useful for treatment or prevention of HIV, a symptomassociated with HIV infection, or other disease or disease symptom suchas a secondary infection or unusual tumor such as herpes,cytomegalovirus, Kaposi's sarcoma and Epstein-Barr virus-relatedlymphomas among others, that can result in HIV immuno-compromisedsubjects.

In certain embodiments of the invention, one or more pyrazolidinylcompounds of the invention including those of Formulae I and II aboveare used in conjunction with a standard HIV antiviral treatmentregimens. This combination is advantageous in that the compound(s) ofthe formulae herein can activate latent HIV infected cells to replicateby stimulating lytic viral replication, thus making them susceptible tothe co-administered standard HIV antiviral treatment regimens. In thismanner, the latent or secondary reservoirs of HIV-infected cells aredepleted through “controlled” activation (rather then serendipitous oruncontrolled activation), resulting in more complete elimination ofinfection. In another aspect, the treatment methods herein includeadministration of a so-called HIV-drug “cocktail” or combinationtherapy, wherein a combination of reverse transcriptase inhibitor(s) andHIV protease inhibitor(s) is co-administered.

For antiviral therapies, in a particular aspect, pyrazolidinyl compoundsof the invention can be administered to HIV infected individuals or toindividuals at high risk for HIV infection, for example, those havingsexual relations with an HIV infected partner, intravenous drug users,etc.

Compounds of the invention can be administered by a variety of routes,such as orally or by injection, e.g., intramuscular, intraperitoneal,subcutaneous or intravenous injection, or topically such astransdermally, vaginally and the like.

In a particular embodiment, the compounds of the invention areadministered intravenously. Compounds of the invention may be suitablyadministered to a subject in the protonated and water-soluble form,e.g., as a pharmaceutically acceptable salt of an organic or inorganicacid, e.g., hydrochloride, sulfate, hemi-sulfate, phosphate, nitrate,acetate, oxalate, citrate, maleate, mesylate, etc. If the compound hasan acidic group, e.g. a carboxy group, base additional salts may beprepared. Lists of additional suitable salts may be found, e.g., inRemington's Pharmaceutical Sciences, 17^(th) ed., Mack PublishingCompany, Easton, Pa.

Compounds of the invention can be employed, either alone or incombination with one or more other therapeutic agents as discussedabove, as a pharmaceutical composition in mixture with conventionalexcipient, i.e., pharmaceutically acceptable organic or inorganiccarrier substances suitable for oral, parenteral, enteral or topicalapplication which do not deleteriously react with the active compoundsand are not deleterious to the recipient thereof. Suitablepharmaceutically acceptable carriers include but are not limited towater, salt solutions, alcohol, vegetable oils, polyethylene glycols,gelatin, lactose, amylose, magnesium stearate, talc, silicic acid,viscous paraffin, perfume oil, fatty acid monoglycerides anddiglycerides, petroethral fatty acid esters, hydroxymethyl-cellulose,polyvinylpyrrolidone, etc. The pharmaceutical preparations can besterilized and if desired mixed with auxiliary agents, e.g., lubricants,preservatives, stabilizers, wetting agents, emulsifiers, salts forinfluencing osmotic pressure, buffers, colorings, flavorings and/oraromatic substances and the like which do not deleteriously react withthe active compounds.

Pharmaceutical compositions of the invention include a compound of theinvention packaged together with instructions (written) for therapeuticuse of the compound, particularly to treat a subject suffering from orsusceptible to cancer. Most preferred method of treating the patientwith the pharmaceutical compositions of the invention, is administrationof the compositions intravenously. However, other routes ofadministration of the pharmaceutical compositions can be used.

For oral administration, pharmaceutical compositions containing one ormore compounds of the invention may be formulated as e.g. tablets,troches, lozenges, aqueous or oily suspensions, dispersible powders orgranules, emulsions, hard or soft capsules, syrups, elixers and thelike. Typically suitable are tablets, dragees or capsules having talcand/or carbohydrate carrier binder or the like, the carrier preferablybeing lactose and/or corn starch and/or potato starch. A syrup, elixiror the like can be used wherein a sweetened vehicle is employed.Sustained release compositions can be formulated including those whereinthe active component is protected with differentially degradablecoatings, e.g., by microencapsulation, multiple coatings, etc.

For parenteral application, e.g., sub-cutaneous, intraperitoneal orintramuscular, particularly suitable are solutions, preferably oily oraqueous solutions as well as suspensions, emulsions, or implants,including suppositories. Ampoules are convenient unit dosages.

The actual amounts of active compounds used in a given therapy will varyaccording to the specific compound being utilized, the particularcompositions formulated, the mode of application, the particular site ofadministration, etc. Optimal administration rates for a given protocolof administration can be readily ascertained by those skilled in the artusing conventional dosage determination tests conducted with regard tothe foregoing guidelines. See also Remington's Pharmaceutical Sciences,supra. In general, a suitable effective dose of one or more compounds ofthe invention, particularly when using the more potent compound(s) ofthe invention, will be in the range of from 0.01 to 100 milligrams perkilogram of bodyweight of recipient per day, preferably in the range offrom 0.01 to 20 milligrams per kilogram bodyweight of recipient per day,more preferably in the range of 0.05 to 4 milligrams per kilogrambodyweight of recipient per day; or any dosage range in which the lowend of the range is any amount between 0.01 mg/kg/day and 90 mg/kg/dayand the upper end of the range is any amount between 1 mg/kg/day and 100mg/kg/day (e.g., 0.5 mg/kg/day and 2 mg/kg/day, 5 mg/kg/day and 20mg/kg/day). The desired dose is suitably administered once daily, orseveral sub-doses, e.g. 2 to 4 sub-doses, are administered atappropriate intervals through the day, or other appropriate schedule.Such sub-doses may be administered as unit dosage forms, e.g.,containing from 0.05 to 10 milligrams of compound(s) of the invention,per unit dosage; or any dosage range in which the low end of the rangeis any amount between 0.05 mg/day and 400 mg/day and the upper end ofthe range is any amount between 1 mg/day and 500 mg/day (e.g., 5 mg/dayand 100 mg/day, 150 mg/day and 500 mg/day).

A “pharmaceutically acceptable derivative or prodrug” means anypharmaceutically acceptable salt, ester, salt of an ester, or otherderivative of a compound of this invention which, upon administration toa recipient, is capable of providing (directly or indirectly) an activecompound of this invention. Particularly favored derivatives andprodrugs are those that increase the bioavailability of the compounds ofthis invention when such compounds are administered to a mammal (e.g.,by allowing an orally administered compound to be more readily absorbedinto the blood) or which enhance delivery of the parent compound to abiological compartment (e.g., the brain or central nervous system)relative to the parent species. Preferred prodrugs include derivativeswhere a group which enhances aqueous solubility or active transportthrough the gut membrane is appended to the structure of formulaedescribed herein. See, e.g., Alexander, J. et al. Journal of MedicinalChemistry 1988, 31, 318-322; Bundgaard, H. Design of Prodrugs; Elsevier:Amsterdam, 1985; pp 1-92; Bundgaard, H.; Nielsen, N. M. Journal ofMedicinal Chemistry 1987, 30, 451-454; Bundgaard, H. A Textbook of DrugDesign and Development; Harwood Academic Publ.: Switzerland, 1991; pp113-191; Digenis, G. A. et al. Handbook of Experimental Pharmacology1975, 28, 86-112; Friis, G. J.; Bundgaard, H. A Textbook of Drug Designand Development; 2 ed.; Overseas Publ.: Amsterdam, 1996; pp 351-385;Pitman, I. H. Medicinal Research Reviews 1981, 1, 189-214.

The invention also provides kits for treatment or prevention of adisease or disorder (or symptoms) thereof associated withubiquitination. In one embodiment, the kit includes an effective amountof a compound herein in unit dosage form, together with instructions foradministering the compound to a subject suffering from or susceptible toa disease or disorder or symptoms thereof associated withubiquitination, wherein the effective amount of a compound is asdescribed herein. In preferred embodiments, the kit comprises a sterilecontainer which contains compound; such containers can be boxes,ampules, bottles, vials, tubes, bags, pouches, blister-packs, or othersuitable container form known in the art. Such containers can be made ofplastic, glass, laminated paper, metal foil, or other materials suitablefor holding medicaments. The instructions will generally includeinformation about the use of the compound for treatment of a disease ordisorder or symptoms thereof associated with ubiquitination, includingtreatment of cell proliferative diseases and disorders, and/or treatmentof a disease or disorder where inflammation or an immune response isexhibited and/or treatment of viral infections particularly retroviralinfections such as HIV infections; in preferred embodiments, theinstructions include at least one of the following: description of thecompound; dosage schedule and administration for treatment of a diseaseor disorder or symptoms; precautions; warnings; indications;counter-indications; overdosage information; adverse reactions; animalpharmacology; clinical studies; and/or references. The instructions maybe printed directly on the container (when present), or as a labelapplied to the container, or as a separate sheet, pamphlet, card, orfolder supplied in or with the container.

As discussed above, the invention also provides methods (also referredto herein as “screening assays”) for identifying candidate compoundsuseful for treatment against cancer cells or other undesired cellproliferation. Screening assays can be adapted to a high throughputformat to enable the rapid screening of a large number of compounds.Assays and screening methods can be used for identification of compoundspossessing E1-specific, Mdm2-specific and/or general inhibition ofubiquitin enzyme inhibitory activity. Thus, in accordance with theinvention, methods are provided to screen candidate compounds whichexhibit potential anti-cancer activity by measuring p53 stability intransformed cells and/or apoptosis and cell death.

The ubiquitin activating enzyme (E1) forms a high energy thioesterlinkage with ubiquitin. Ubiquitin is then transferred to a reactivecysteine residue of one of many ubiquitin conjugating enzymes known asUbc or ubiquitin E2 enzymes. The final transfer of ubiquitin to a targetprotein involves one of many ubiquitin protein ligases (E3s). Mdm2 issuch a ubiquitin ligase that mediates the transfer of ubiquitin to p53.

Mdm2 protein binds tumor suppressor p53 and targets it forubiquitination and proteosome-mediated degradation. Mdm2 is a RINGfinger-containing E3 for p53. Mdm2 also catalyzes self-ubiquitination,and thus regulates intracellular levels of both p53 and itself. Withoutwishing to be bound by theory, molecules which inhibit the activity ofubiquitin E1, and thus inhibit Mdm2 activity, including the activity ofMdm2 with respect to p53 could be important in identifying potentialdrug compounds that affect p53 stability. Similarly, interference withthe expression of E1 by a candidate drug compound can identifyanti-tumor compounds that can be further analyzed using ahigh-throughput assay described below. As a theoretical illustrativeexample, expression may be down regulated by administering smallmolecules and peptides which specifically inhibit E1 expression can alsobe used.

In theory, such inhibitory molecules can be identified by screening forcompounds which interfere with the formation of thiolester linkagesbetween ubiquitin and E1 where one of the binding partners is bound to asolid support and the other partner is labeled. Antibodies specific forepitopes on ubiquitin or E1 which are involved in the bindinginteraction will interfere with such binding. Solid supports which maybe used include any polymers which are known to bind proteins. Thesupport may be in the form of a filter, column packing matrix orsephadex beads. Labeling of proteins can be accomplished according tomany techniques. Radiolabels, enzymatic labels, and fluorescent labelscan be used. Alternatively, both ubiquitin and E1 may be in solution andbound molecules separated from unbound subsequently. Any separationtechnique may be employed, including immunoprecipitation orimmunoaffinity separation with an antibody specific for the unlabeledbinding partner.

The ability of a compound to inhibit E1 activity may also be examined bydetermining the ability of the compound to inhibit Mdm2autoubiquitination, which is dependent on E1, as well as E2. For invitro assays Mdm2 can be expressed as a GST fusion. This allows for ahigh level of expression of protein that can be purified on glutathioneSepharose. Detection of ubiquitination of Mdm2 can be accomplished, forexample, using ³²P-labeled ubiquitin, Western blotting withanti-ubiquitin, or by looking at a shift in the molecular weight of GSTfusion by Western blotting with anti-GST. A variety of in vitro assaysthat measure levels of self-ubiquitinated Mdm2 can be employed, such asfor example, immunoprecipitation of ubiquitinated Mdm2; gel assayswherein the amount of ubiquitinated Mdm2 is measured by densitometricscanning or where covalent attachment of radio-labeled or otherwisetagged ubiquitin to Mdm2 or p53 is measured; Western blot analysis, orother known techniques such as ELISA, immunoprecipitation, RIA, and thelike. Candidate compounds that inhibit self-ubiquitination of Mdm2, asdescribed in detail in the Examples which follow, are detected by ashift in molecular weight either of Mdm2 or of ubiquitin that becomescovalently attached to Mdm2. (See for example Lorrick KL., et al., Proc.Natl. Acad. Sci. USA, 1999, 96:11364-11369; Fang S., et al., J. Biol.Chem., 2000, 275(12)8945-8951; Ryan KM., et al., Curr. Op. Cell Biol.,2001, 13:332-337; which are herein incorporated by reference in theirentirety). Mdm2 self-ubiquitination assays are run (see for example theresults described in the Examples section) in the presence or absence ofa known amount of candidate compound. An aliquot of each of the test andcontrol reactions are run on a standard SDS-PAGE gel. Test reactionswhereby the candidate compounds inhibit the self-ubiquitination of Mdm2will have a decrease in high molecular weight ubiquitinated Mdm2.

In cellular assays, endogenous or transfected Mdm2 is used. Fortransfected Mdm2, ubiquitination is evaluated by an upward smear byanti-Mdm2 Western blotting after resolution of cell lysates on SDS-PAGE.Alternatively, immunoprecipitation can be accomplished by subjectinglysates from cells (treated and untreated cells) to anti-Mdm2, followedby Western Blotting and detecting ubiquitination by using anti-ubiquitinantibodies. Preferred screening methods comprise identifying a candidatecompound based on assessment of p53 stabilization (e.g. half life ofp53) and steady state levels, and the level of Mdm2, as compared to acontrol, e.g. normal (non-cancer cells).

Steady-state levels of p53 and Mdm2 in the cells can be determined by anumber of approaches. For instance, lysates containing cellular proteincan be immunoprecipitated with, for example, a rabbit anti-p53polyclonal antibody or Mdm2 polyclonal antibody, blotted ontopolyvinylidenedifluoride (PVDF) membranes and probed with a monoclonalantibody cocktail comprising, for example, monoclonal antibodies tovarious epitopes of p53, or Mdm2. Such antibodies are commerciallyavailable. Immunoblot analyses of cellular extracts, taken at differenttime points after treatment with a candidate compound is determinativeof the half-life of p53 as compared to normal controls. Thus, increaseor decrease in levels of p53 over periods of time is determinative ofp53 stability based on its half-life and steady state levels. Thelysates can be further purified, for example, by immunoprecipitation ofp53 and/or Mdm2 directly or indirectly of Mdm2 and p53, or by affinitychromatography. Thus, candidate compounds that inhibit Mdm2 ubiquitinligase activity, can be screened for any effect on p53 stability.

Cell-based assays include model systems where primary human epithelialcells (“normal cells”) are compared to the same cells expressing theadenovirus E1A oncogene (“transformed cells”). Activation of p53 was nottoxic to normal cells, but activation of p53 in transformed cellsinduces p53-mediated apoptosis. High concentrations of wild type (wt)p53 protein can induce apoptosis in a variety of different tumor cells.Potential inhibitors of Mdm2 would regulate the stability and functionof p53 and Mdm2. Preferably the assays measure number of cellsundergoing apoptosis due to Mdm2 induced p53 degradation in tumor cellsin the presence or absence of candidate compounds as compared to normalcells in the presence or absence of candidate compounds. An increase inthe number of these cells undergoing apoptosis in the presence ofcandidate compounds in tumor cells, as compared to normal untreatedcells is indicative of a potential anti-tumor compound. Preferably acandidate compound increases apoptosis of tumor cells by at least 20% ascompared to a control (no candidate compound administered), morepreferably a candidate compound increases apoptosis of a tumor cell byat least about 30%. 40%, 50%, 60%, 70%, 80%, 90% or 100% as compared toa control (no candidate compound administered). That is, for example 80%increase of apoptosis refers to a decrease in the numbers of cells stillsurviving as compared to the controls.

Apoptosis can be measured by a variety of techniques. For example,apoptosis can be measured by determination of cell phenotype. Phenotyperefers to how the cell looks, typically microscopically, but gross ormacroscopic appearance can be observed. The phenotype changes dependingon the growth rate of the cells. For instance, the microscopicmorphology of cells that are rapidly dividing and growing is differentthan that of cells undergoing cell death by apoptosis. Determination ofcell phenotype is well within the ability of one of ordinary skill inthe art.

There are also a number of biochemical assays that can be used to detectapoptosis, such as “laddering” of the cellular DNA. When testingcompounds for the ability to induce apoptosis, cell death (notcytostasis) is an endpoint of a compound application to the cell. Aclassic signature of apoptosis is the cleavage of nuclear DNA intonucleosomal subunits. On gels, this gives rise to the appearance of aladder as nucleosomal units are sequentially cleaved from DNA.Observation of a classic DNA ladder is indicative of apoptosis. Forexample, cells are lysed and the high molecular weight DNA is removed bycentrifugation. The aqueous phase is treated with proteinase K to digestproteins. After a phenol/chloroform extraction, the pellet is dissolvedin deionized water and treated with 500 μg/ml RNaseA. The DNA is run ona 2% agarose minigel. Observation for a classic DNA ladder is made and aphotograph can be taken. Cell death is verified by the demonstration ofDNA as represented by the ladder configurations on the gel (see forexample, White E., et al. 1984, J. Virol. 52:410). There are also avariety of other assays available for apoptosis such as “TUNEL” assays(see Gavrieli, Y., et al. (1992) J. Cell. Biol. 119:493).

As discussed above, the invention assays and screening methods foridentification of other compounds possessing anti-cancer activity,including Mdm2-specific and/or general inhibition of ubiquitin enzymeinhibitory activity. Thus, in accordance with the invention, methods areprovided to screen candidate compounds which exhibit potentialanti-cancer activity by measuring p53 stability in transformed cellsand/or apoptosis and cell death.

We also have found that compounds of the invention are not readilyremoved (e.g. washed away by buffer solutions) once added to E1.Additionally, we have found that biological activity of compounds of theinvention as disclosed herein can be substantially inhibited orprevented by treatment with an excess of reduced glutathione. Thisindicates that the compounds can act as a nucleophile for the activesite thiol of E1 (e.g., a central double bond of a compound can serve asMichael-acceptor for the nucleophilic thiol in a Michael-type reaction).

We have further found that compounds of the invention can prevent orinhibit activation of Nfkb. In particular, such inhibition of Nfkbactivation has been shown in cell-based reporter assay.

This invention is further illustrated by the following examples whichshould not be construed as limiting. The contents of all references,patents and published patent applications cited throughout thisapplication, as well as the figures, are incorporated herein byreference.

Example 1 Evaluation of Small Molecules that Inhibit Mdm2Autoubiquitination

Fifty-two compounds that significantly inhibited autoubiquination ofGST-Mdm2 were selected for further evaluation in the laboratory using agel-based ubiquitination assay utilizing ³²P-labeled ubiquitin. Most ofthese compounds inhibited Mdm2 autoubiquitinzation (some examples areshown in FIG. 1A). Since Mdm2 autoubiquitination depends on the activityof E1 and E2, some of these might act by inhibiting E1. In fact, somedid block the formation of thiolester linkages between ³²P-labeledubiquitin and E1 (FIG. 1B). The compound4-[4-(5-nitro-furan-2-ylmethylene)-3,5-dioxo-pyrazolidin-1-yl]-benzoicacid methyl acid was active at a concentration of 20-50 μM.

One way that the compounds might inactivate E1 is by alkylating orotherwise irreversibly inactivating active site cysteines. Like E1, E2also uses a cysteine to form thiolester bond with ubiquitin. Inhibitorsthat directly act on the cysteine of E1 might therefore also affect E2activity, and thus function in a relatively non-specific manner. Toevaluate the effect of compounds on E2, we first loaded E1 with³²P-labeled ubiquitin, and then added E2 with the compounds to examinewhether formation of E2-ubiquitin complex is prevented. As shown in FIG.2A, several compounds identified in the screen effectively inhibitedformation of E2-ubiquitin complex. However, the compound4-[4-(5-nitro-furan-2-ylmethylene)-3,5-dioxo-pyrazolidin-1-yl]-benzoicacid methyl acid and the compound designated as “compound 41” did notaffect transfer of ubiquitin from E1 to E2, indicating that thesecompounds do not function to non-specifically inhibit thiols. Thesefindings are reinforced in FIG. 2B, where E2 thiolester formation isinhibited by the compound4-[4-(5-nitro-furan-2-ylmethylene)-3,5-dioxo-pyrazolidin-1-yl]-benzoicacid methyl acid and compound 42 if the E1 is exposed to these compoundsbefore loading with ubiquitin (lower panel), but not when the E1 ispreloaded with ubiquitin (upper panel).

It was then evaluated whether4-[4-(5-nitro-furan-2-ylmethylene)-3,5-dioxo-pyrazolidin-1-yl]-benzoicacid methyl acid blocks autoubiquitination of both RING finger E3s(Mdm2) and HECT E3s (Nedd4) in vitro. As shown in FIG. 2C (left panel),4-[4-(5-nitro-furan-2-ylmethylene)-3,5-dioxo-pyrazolidin-1-yl]-benzoicacid methyl acid can prevent generation of high molecular weight speciespromoted by Mdm2 in a dose-dependent manner. As predicted, the compoundalso inhibits the autoubiquitination of Nedd4 (right panel), whereas theMdm2 inhibitor 98CO7(10-(-3-chloro-phenyl)-7-nitro-10H-pyrimido[4,5-b]quinoline-2,4-dione)only has very moderate effects. These results are consistent with aneffect at the level of E1.

Example 2 E1 Inhibitor Inactivates E1 and Blocks Cyclin E Degradation InVitro

Cytosolic extracts from cells (S-100) contain all the components forubiquitination and proteasomal degradation. To further evaluate4-[4-(5-nitro-furan-2-ylmethylene)-3,5-dioxo-pyrazolidin-1-yl]-benzoicacid methyl acid, we made use of in vitro translated cyclin E, which isdegraded in S-100 in a time-dependent manner (FIG. 3, upper panel, lanes1-4). Both4-[4-(5-nitro-furan-2-ylmethylene)-3,5-dioxo-pyrazolidin-1-yl]-benzoicacid methyl acid and the proteasome inhibitor MG132 block cyclin Edegradation (FIG. 3, upper panel, lanes 5-12). However, when purifiedexogenous E1 is added to the reaction mixture,4-[4-(5-nitro-furan-2-ylmethylene)-3,5-dioxo-pyrazolidin-1-yl]-benzoicacid methyl acid-mediated inhibition of cyclin E degradation wasprevented (FIG. 3, lower panel, lanes 5-8). In contrast, when the blockin degradation is distal to ubiquitination, as is the case withproteasome inhibition, addition of exogenous E1 is unable to overcomethe block in cyclin E degradation (FIG. 3, lower panel, lanes 9-12).

Example 3 E1 Inhibitor Prevents TNF-Induced Degradation of IκBα

In order to evaluate4-[4-(5-nitro-furan-2-ylmethylene)-3,5-dioxo-pyrazolidin-1-yl]-benzoicacid methyl acid in a cell-based system, the NFκB pathway was examined.NFκB is a critical transcription factor that controls expression ofvarious genes involved in inflammation and immunity. In response topro-inflammatory signals, the NFκB inhibitor IκBα is rapidlyphosphorylated by IκB kinase (IKK), which leads to IκBαubiquitinationand its proteasomal degradation. Degradation of IκB allows NFκB to enterthe nucleus and thereby regulate gene transcription. Ubiquitination hasalso more recently been shown to play important roles in IKK activation.IKK is activated by TRAF6, which must first be ubiquitinated with aK63-linked polyubiquitin chain.

As with the proteasome inhibitor ALLN,4-[4-(5-nitro-furan-2-ylmethylene)-3,5-dioxo-pyrazolidin-1-yl]-benzoicacid methyl acid prevents TNFα-induced IκBα degradation (FIG. 4A).Moreover,4-[4-(5-nitro-furan-2-ylmethylene)-3,5-dioxo-pyrazolidin-1-yl]-benzoicacid methyl acid also blocks IκBα phosphorylation following TNFαtreatment (FIG. 4B—1 minute stimulation), indicating that the compoundacts upstream of IKK. To determine whether4-[4-(5-nitro-furan-2-ylmethylene)-3,5-dioxo-pyrazolidin-1-yl]-benzoicacid methyl acid blocks ubiquitination of TRAF6 in response to TNFα,TRAF6 was immunoprecipitated from the T cell leukemia Jurkat after TNFαtreatment, followed by immunoblotting (FIG. 4C). TNFα inducedubiquitination of TRAF, which was effectively inhibited by4-[4-(5-nitro-furan-2-ylmethylene)-3,5-dioxo-pyrazolidin-1-yl]-benzoicacid methyl acid.

Example 4 E1 Inhibitor Prevents P53 Degradation and Induces Apoptosis inTransformed Cells

Since compound 41 inhibits autoubiquitination of Mdm2 in vitro, we nextasked whether it increases cellular Mdm2 and p53. Immunoblottingrevealed that, after six hours treatment, both Mdm2 and p53 areincreased in cells (FIG. 5A). The p53 was found to be transcriptionallyactive, as it activated a p53-driven luciferase reporter to a levelcomparable to adriamycin (FIG. 5B).

While p53 induces apoptotic cell death in many tumor cells, it generallyonly induces growth arrest in untransformed cells. This has been therationale for many studies targeting the p53 system. We found that theE1 inhibitor causes growth arrest in untransformed retinal pigmentepithelial cells (FIG. 6A), but strikingly kills myeloma cells in adose-dependent manner (FIG. 6B). Furthermore, it only kills MEFs (mouseembryonic fibroblasts) that express wild type p53, whereas MEFs fromp53-deficient mice are relatively resistant, indicating the cytotoxicaction of inhibitor4-[4-(5-nitro-furan-2-ylmethylene)-3,5-dioxo-pyrazolidin-1-yl]-benzoicacid methyl acid in these transformed cells is p53 dependent.

Example 5 E1 Inhibitor Prevents Loading of E1 with Ubiquitin in Cells

RPE cells were treated with the E1 inhibitor of4-[4-(5-nitro-furan-2-ylmethylene)-3,5-dioxo-pyrazolidin-1-yl]-benzoicacid methyl acid (designated as E1-41, 50 μM), HLI98C (50 μM) oriodoacetamide 10 nM for 1 hour followed by lysis, SDS-PAGE under eithernon-reducing (FIG. 7A) or reducing (FIG. 7B) conditions andimmunoblotting with anti-E1. Results are shown in FIGS. 7A and 7B, wherethe E1-41 compound is shown to inhibit the loading of E1 with ubiquitin.Thus, as shown by the data in those figures, the E1-41 compound caninhibit E1-Ub thiol-ester formation in RPE cells.

Example 6 E1 Inhibitor Inhibits Proteasome Inhibito-Induced Accumulationof Ubitquitylated Proteins

U2O cells were treated with the E1 inhibitor of4-[4-(5-nitro-furan-2-ylmethylene)-3,5-dioxo-pyrazolidin-1-yl]-benzoicacid methyl acid (designated as E1-41, 50 μM) and proteasome inhibitor(ALLN 50 μM) as indicated for four hours followed by lysis, SDS-PAGEunder either non-reducing or reducing conditions and immunoblotting withanti-E1. Results are shown in FIG. 8, where the E1-41 compound is shownto inhibit the accumulation of ubiquiylated proteins in the proteasomeinhibitor-treated cells.

Example 7 In Vitro Assays for Ubiquitination and Thiol-Ester BondFormation

The following in vitro assays were employed as disclosed herein.

a. “Standard Mdm2 In Vitro Ubiquitination Assay” (E1+E2+E3 assay)

5 pmole per experimental point of bacterially expressed GST-Mdm2 (orGST-Nedd) is coupled to glutathione Sepharose (GS) for 30 minutes atroom temperature with tumbling, followed by 3× wash with 50 mM Tris pH7.5. Following this, 201 of 1× buffer is added (40 μl 10× reactionbuffer*, 40 μl 10×PCK**, 320 μl dH₂O). The test compound in DMSO is thenadded to the desired concentration with an equal volume of DMSO used asa control. Samples are incubated with shaking for 1 hr at 23° C. Tocarry out the reaction, a pre-made cocktail of Rabbit E1 (Calbiochem#6620700)/UbCH5B/³²P Ub cocktail (1 μl/0.5 l/1 μl) is added followed by15 minutes shaking at 30° C. The reaction is terminated by addition of 8μl 4× reducing SDS-PAGE loading buffer. After dissociating proteins fromthe beads at 100° C. for 2 minutes, samples are resolved on 6% PAGEfollowed by exposure of the dried gel to phosphor screen. Note: ³²P Ubis derived from GST-Ub that has been engineered to include a PKAphosphorylation site. This fusion protein is purified on glutathioneSepharose, phosphorylated, following this, the ³²P Ub ubiquitin iscleaved and purified away from the thrombin.

* 10× buffer

500 mM Tris (pH 7.5) 2 mM ATP 10 mM MgCl₂ 1 mM DTT

10 mM creatine phosphate (Sigma P4635) (45 mg/10 ml).

** 10×PCK

Sigma C7886, 1000 U, reconstitute in 200 μl 10 mM Tris pH 8.0.

b. “E1 Only” Assay.

-   -   2 μl rabbit E1+12 μl of 1× reaction buffer are mixed together        with the test compound followed by addition of 11 of ³²P Ub.        After incubating for 10 minutes at room temperature, the samples        are denatured using loading buffer without reducing agent and        subjected to SDS-PAGE under non-reducing conditions to maintain        thiol-ester linkages and exposure as above.

c. E1+E2 Assay with Immobilized E2

20 pmoles of bacterially-expressed GST-UbCH5B are bound to GS beads for30 minutes at room temperature. After washing in 50 mM Tris, pH 7.5, thetest compounds were incubated with the beads in 20 μl of 1× reactionbuffer at 23° C. for 1 hour. Rabbit E1/32P Ub cocktail (1 μl/1 μl) wasthen added to the mixture to incubate for another 60 minutes withshaking at 23° C. This is followed by resolution by SDS-PAGE undernon-reducing conditions and exposure as above.

d. In Vitro p53 Ubiquitination Assay

p53 protein from SAOS-p53 inducible cell lysate is purified from cellsusing GST-Mdm2 (5 pmol) pre-bound to GS beads. Samples are thenincubated with test compounds as above. Subsequently 2 μl rabbit E1, 1μl UbCH5b, and 10 μg of ubiquitin are added. After reaction for 15 minat 23° C., samples are subject to SDS-PAGE under reducing conditions,transferred to nitrocellulose membranes and immunoblotted with anti-p53(DO-1) followed by ECL using standard techniques.

Example 8 E1 Inhibitor Interacts with Ubiquitin E1 Covalently

A number of the steps involved in regulating protein ubiquitination areknown. Among those steps, the ubiquitin activating enzyme (E1) initiallyforms a high energy thioester linkage with ubiquitin. Ubiquitin is thentransferred to a reactive cysteine residue of one of many ubiquitinconjugating enzymes known as Ubc or ubiquitin E2 enzymes.

Here, the interaction of the E1 inhibitor4-[4-(5-nitro-furan-2-ylmethylene)-3,5-dioxo-pyrazolidin-1-yl]-benzoicacid methyl acid (designated as E1-41) with ubiquitin E1 was examined.

Bead immobilized His₆-E1 was treated with E1 inhibitor4-[4-(5-nitro-furan-2-ylmethylene)-3,5-dioxo-pyrazolidin-1-yl]-benzoicacid methyl acid (E1 41) at a range of concentrations (0-50 μm) asindicated in FIG. 9A. The beads were subjected to wash (+ wash) or nowash (− wash) conditions. Panel A shows the results of protein blottingfor ubiquitin E1 enzyme. In both the washed and unwashed conditions,identical band patterns of E1-Ub detection are seen, indicating that theE1 41 compound cannot be washed away. These results suggest that the E141 compound and ubiquitin E1 interact in a covalent manner.

The ability of a compound to inhibit E1 activity may come from theability of the compound to interfere with the formation of thiolesterlinkages between ubiquitin and E1. Next, the biological activity of E141 was tested to examine if it can be inhibited or prevented bytreatment with an excess of reduced glutathione. FIG. 9B shows theresults of an experiment in which bead immobilized His₆-E1 was treatedin the presence or absence of E1 inhibitor E1 41 (50 μM), and thepresence or absence of glutathione (GSH) at a range of doses (0.1-10mM). Panel B shows the results of protein blotting for ubiquitin E1enzyme. The inhibitory action of E1 41 can be prevented by the additionof reduced glutathione (GSH) in a dose-dependent manner. Thus, E1 41 canact as a target for nucleophilic attack by active site thiol of E1(e.g., a central double bond of a compound can serve as Michael-acceptorfor the nucleophilic thiol in a Michael-type reaction). Taken together,the data indicates that E1 41 interacts with the ubiquitin E1 in acovalent manner.

Example 9 E1 Inhibitor Blocks IL-1 Induced Activation of NFκB

NFκB is a regulator of cell proliferation and survival. Accordingly,misregulation of NFκB plays a role in cancer and other proliferativediseases.

Here, the ability of4-[4-(5-nitro-furan-2-ylmethylene)-3,5-dioxo-pyrazolidin-1-yl]-benzoicacid methyl acid (E1-41) to prevent activation of NfκB in cells wastested.

HeLa cells (human epithelial cells) were transfected with a NFκBresponse element-driven luciferase reporter. The cells were treated withE1 41 (50 μM) for 10 minutes, or dimethyl sulfoxide (DMSO) control.Interleukin 1 (IL-1) was added to the cells for 2 hours. IL-1 was addedat concentrations ranging from 0-1.0 ng/ml to induce activation of NFκB.An assay for luciferase activity was carried out according to themethods as described in the commercially available PROMEGA system forluciferase detection. FIG. 10 shows that in cells treated with E1-41,there was a reduction of luciferase activity (RLU×1000), indicating thatE1 41 blocked IL-1 induced activation of NFκB.

These results indicate that E1 41 is able to prevent activation of NFκB.

All references cited herein, whether in print, electronic, computerreadable storage media or other form, are expressly incorporated byreference in their entirety, including but not limited to, abstracts,articles, journals, publications, texts, treatises, technical datasheets, internet web sites, databases, patents, patent applications, andpatent publications.

EQUIVALENTS

Those skilled in the art will recognize, or be able to ascertain usingno more than routine experimentation, many equivalents to the specificembodiments of the invention described herein. Such equivalents areintended to be encompassed by the following claims.

1. A method of treating a mammal in need of treatment or prevention of adisorder or disease that is responsive to inhibition of ubiquitin E1comprising: administering to the subject an effective amount of one ormore pyrazolidinyl compounds of Formula (I), or a pharmaceuticallyacceptable salt, solvate or hydrate thereof:

wherein, each X is independently O, S, or NR¹; each R¹ is independentlyH, alkyl, alkenyl, alkynyl, cycloalkyl, aralkyl, heteroaralkyl, C(O)R,C(O)OR, or C(O)NRR², each optionally substituted with a substituent;each R² is independently H, alkyl, alkenyl, alkynyl, cycloalkyl,aralkyl, or heteroaralkyl, each optionally substituted with asubstituent; each R is independently H, alkyl, alkenyl, alkynyl,cycloalkyl, aralkyl, or heteroaralkyl, each optionally substituted witha substituent; Y is H, alkyl, alkenyl, alkynyl, cycloalkyl, nitro, orhalogen; wherein the alkyl, alkenyl, alkynyl, cycloalkyl, aralkyl,heteroaralkyl, aryl, or heteroaryl groups may be substituted with H,halogen, nitro, cyano, alkoxy, thioalkoxy, NR³R⁴, S(O)R⁵, or S(O)₂R⁵;wherein each of R³ and R⁴ are independently selected from H, alkyl,aralkyl, or aryl; wherein R⁵ is OH, OR³, NH₂, or NHR³; Z is H, alkyl,alkenyl, alkynyl, cycloalkyl, aralkyl, heteroaralkyl, aryl, heteroaryl,halogen, C(O)R³, C(O)OR³, C(O)SR³, C(O)NR³R⁴, C(S)OR³, C(NR¹)OR³, orC(NR¹)NR³R⁴; and n is 0-5; wherein the disorder or disease that isresponsive to inhibition of ubiquitin E1 is unwanted cell proliferationcaused by loss of p53 activity or treatment of viral infections.
 2. Themethod of claim 1, wherein the pyrazolidinyl compound is of Formula(II), or a pharmaceutically acceptable salt, solvate or hydrate thereof:

wherein, each X is independently O, S, or NR¹; each R¹ is independentlyH, alkyl, alkenyl, alkynyl, cycloalkyl, aralkyl, heteroaralkyl, C(O)R,C(O)OR, or C(O)NRR²; each R² is independently H, alkyl, alkenyl,alkynyl, cycloalkyl, aralkyl, or heteroaralkyl; each R is independentlyH, alkyl, alkenyl, alkynyl, cycloalkyl, aralkyl, or heteroaralkyl. 3.The method of claim 1, wherein the pyrazolidinyl compound is of Formula(I), or a pharmaceutically acceptable salt, solvate or hydrate thereofis

wherein, each X is O, Y is NO₂, n is 1, and Z is halogen or C(O)OR³,wherein R³ is a C₁-C₁₂ straight or branched chain alkyl.
 4. The methodof claim 1, wherein the pyrazolidinyl compound is4-[4-(5-nitro-furan-2-ylmethylene)-3,5-dioxo-pyrazolidin-1-yl]-benzoicacid methyl ester.
 5. The method of claim 1, wherein the disorder ordisease that is responsive to inhibition of ubiquitin E1 is unwantedcell proliferation caused by loss of p53 activity.
 6. The method ofclaim 5, wherein the unwanted cell proliferation caused by loss of p53activity is myeloma.
 7. The method of claim 5, wherein the loss of p53activity is due to increased Mdm2 activity.
 8. The method of claim 7,wherein the unwanted cell proliferation caused by loss of p53 activityis a solid tumor or a disseminated cancer.
 9. The method of claim 8,wherein the tumor is a cancer of the lung, prostate, breast, liver,colon, breast, kidney, pancreas, brain, skin, testes or ovaries,leukemia or lymphoma.
 10. The method of claim 5, wherein the unwantedcell proliferation caused by loss of p53 activity is melanoma,carcinoma, leukemia, lymphoma, pediatric sarcoma, sarcoma, breastcancer, ovarian cancer, testicular cancer, prostate cancer, braincancer, head or neck cancer, or lung cancer.
 11. The method of claim 1,wherein the disorder or disease that is responsive to inhibition ofubiquitin E1 is a viral infection.
 12. The method of claim 11, whereinthe viral infection is a retroviral infection.
 13. The method of claim12, wherein the retroviral infection is an HIV infection.